The purpose of this study is to identify genetic loci that affect patterns of alcohol consumption. Individuals with elevated levels of alcohol consumption and their relatives will be studied. Linkage analysis using affected relative pair methods and a systematic screening of the genome for allelic association between genetic markers will be performed. Study participants will undergo an interview, neurologic exam, and phlebotomy in the GCRC. Investigators will assess neurologic capacity, collect data commonly used to make clinical diagnoses of alcoholism, and use these data to retrospectively determine whether these attributes are also associated with specific genetic susceptibility loci.